The process for manufacturing carbon black typically comprises, performing partial pyrolysis of a carbonaceous feedstock, where, the feedstock can be in the form of a gas or liquid. While several processes have been used to obtain carbon black, the most commonly used process is the furnace black process in which carbon black is produced by incomplete combustion of a liquid feedstock comprising heavy petroleum products such as FCC tar, coal tar, and ethylene cracking tar.
In the furnace black process, a hydrocarbon fuel such as natural gas or fuel oil is burned with an excess amount of oxygen typically supplied as a flow of air or an oxygen containing gas in a space having a lining of fire resistant material to produce hot combustion gas. The liquid feedstock to be thermally decomposed and dehydrogenated is sprayed into the hot combustion gas to obtain an aerosol containing carbon black particles suspended in the gas. The carbon black particles in the form of a fluffy powder are separated from the gas and collected. The collected particles are subsequently pelletized by means of conventional pelletizing methods. This carbon black is used in manufacturing pneumatic tires for automobiles and aircraft, as a reinforcing filler for an elastomer, as pigment or colorant for plastic, paint, and printing ink.
The reactors used for the furnace black process generally comprise, a combustion chamber, a mixing chamber, and a reaction chamber, arranged along the axis of the reactor to form a flow path for the reaction media from the combustion chamber through the mixing chamber to the reaction chamber. The liquid feedstock is normally sprayed into the mixing chamber to achieve intensive mixing of the liquid feedstock with the hot combustion gases. This mixture then enters the reaction chamber where the actual carbon black formation process takes place. Finally, the reaction is stopped downstream by spraying water.
The factors that influence the carbon black formation are: the excess air/oxygen in the hot combustion gases, the temperature of the hot combustion gases, efficiency of combustion of the fuel, and the reaction or residence time from the mixing of the feedstock in the hot combustion gases to the completion of the reaction. The combustion efficiency of the fuel depends largely on the mixing of the fuel with the combustion air/oxygen. Typically, the combustion air is preheated to a temperature between 800° C. and mixed with the fuel in the combustion chamber to obtain the hot combustion gases. An improvement in the mixing between the combustion air and the fuel results in increased combustion efficiency and thus higher temperature of hot combustion gases. In general, the higher the temperature of the hot combustion gases, the smaller the particles of carbon black formed.
Several attempts have been made in the past to provide carbon black reactors which improve the furnace black process resulting in, higher efficiency, a better process control, and produce carbon black grades having different fineness. Some of these disclosures are listed in the prior art below:
U.S. Pat. No. 7,625,527 discloses a carbon black reactor which increases the contact efficiency between hot combustion gases and feedstock to increase the conversion rate of the feedstock to carbon black. The carbon black reactor comprises: a combustion zone for generating the hot combustion gases, a reaction zone having two or more points to introduce feedstock therein for producing carbon black by contacting the combustion gases with the feedstock introduced in a plurality of divided flows, a quench zone for stopping the reaction by injecting a coolant, where, the three zones are arrayed laterally in order. The carbon black reactor gives carbon black having uniform characteristics, especially distribution of aggregation size.
CN Patent No. 2341708 discloses a reactor for a carbon black-surface oxidating and fluidizing bed. The reactor comprises: a reactor body, a furnace black inlet, a furnace black outlet, a compound distributing board, an air chamber, an air inlet, and an air outlet, wherein, three to seven baffles are arranged in the reactor comprising four to eight fluidizing chambers to obtain a multi-stage mixed flow. The reactor is simple to manufacture, low cost, and produces carbon black used for coloration in various industries.
U.S. Pat. No. 4,590,040 discloses a carbon black reactor which is adapted to reduce the pressure drop due to excessive turbulence in the pre-combustion zone. The carbon black reactor comprises: a precombustion zone with a cylindrical sidewall and having an upstream end and a downstream end, a plurality of tunnels for conveying combustion gases, the tunnels opening tangentially into the precombustion zone through the sidewall, and a plurality of semicircular ramps positioned in the precombustion zone to define the upstream end for guiding the flow of the tangentially introduced stream of combustion gases. The arrangement prevents a turbulent impact between other tangentially introduced gas streams to reduce the pressure drop therein.
U.S. Pat. No. 4,347,218 discloses an apparatus for producing carbon black grades of different fineness, while in particular preventing thermal overstressing of the reactor in the intake area of hydrocarbon and air. The apparatus comprises: a reactor including a reaction chamber for forming carbon black, a plurality of unjacketed feed units for supplying air to the reaction chamber and spraying hydrocarbon into the air near a discharge end, and a heat exchanger for controlling the temperature of the reactor output gases and carbon black produced therein.
US Application No. 2004213728 discloses a process for the production of furnace black in a furnace black reactor having a flow axis. The process comprises: introducing fuel and combustion air into a gas burner, jetting steam axially through the gas burner, producing thereby a flow of hot combustion gases in a combustion chamber; feeding the hot combustion gases along the flow axis from the combustion chamber through a narrow point into a reaction zone, mixing carbon black raw material into the flow of hot combustion gases upstream of, inside, or downstream of the narrow point; stopping the reaction downstream in the reaction zone by spraying water. The process produces deep-colored furnace blacks in the furnace reactor.
The prior art listed above discloses carbon black reactors adapted to provide an increased process efficiency, enhanced process control or produce carbon black grades of different fineness. The present invention provides one such carbon black reactor, mainly adapted to enhance mixing between the combustion air/oxygen and fuel, to increase the combustion efficiency and provide hot combustion gases having a higher temperature. Further, the present invention provides a carbon black reactor comprising means that allow higher feedstock flow rate through the reactor, while maintaining the quality parameters of the carbon black.